The present invention relates to a photoelectric conversion apparatus and photoelectric conversion method of receiving, e.g., optical image information of an original and outputting an electrical signal, an image information processing apparatus and image information processing method of processing an electrical signal from the photoelectric conversion apparatus, and an image forming apparatus such as an electronic copying machine, which has the image information processing apparatus to form an image.
Conventionally, in controlling devices, for example, a CCD (photoelectric conversion element) for image reading in an image forming apparatus such as an electronic copying machine or a facsimile apparatus, as the read speed increases, the pixel sending frequency becomes high, and signals are more difficult to process. Hence, pixel sending in the image area of a CCD is divisionally performed for odd components (ODD) and even components (even) to realize high-speed processing.
A conventional preprocessing system for signals of two channels output from a 2-channel output CCD processes output signals from the CCD divisionally for even and odd components through one signal transmission path (processing path).
In such a preprocessing system, image signals which have undergone signal amplification processing and A/D conversion processing are input to a scanner control ASIC through two channels for even and odd components each comprising a pixel signal of 8 bits and then synthesized into one channel first. With this processing, image data of one line have the same pixel array as that of the CCD.
The image data synthesized into one channel are subjected to shading processing to correct in units of pixels the influence of deviation in density gradient of each pixel of the image data, which is generated in association with the image density, i.e., a variation in illuminance, a variation in sensitivity of each light-receiving element (e.g., a photodiode) of the CCD, and a dark current generated in the light-receiving elements of the CCD.
The shading-corrected image data are bit-inverted and directly transferred to an image processing ASIC. In the image processing ASIC, a series of data processing operations by image processing, including filtering processing, range correction processing, magnification conversion (enlargement/reduction) processing, xcex3 correction density conversion processing, and gradation processing, are performed.
In the conventional-preprocessing system using the 2-channel output CCD, even and odd components of output signals from the CCD are processed through one signal transmission path (processing path). In this system arrangement, a factor to adversely affect the image density is only a deviation in density gradient of each pixel of the image data, which is generated in association with so-called image density, i.e., the influence of a variation in illuminance, a variation in sensitivity of each light-receiving element of the CCD, and a dark current generated in the light-receiving elements of the CCD. The influence of this deviation, can be corrected by shading processing.
However, the 2-channel-output CCD has a limitation on its processing speed and therefore cannot meet a recent requirement for high-speed processing for a large number of originals.
When a preprocessing system is constructed using a 4-channel output CCD coping with high-speed processing on the basis of the arrangement of the preprocessing system with the 2-channel output CCD, the influence of the difference in signal transmission path (processing path) due to the system arrangement or the internal, structure of the chip of the CCD or amplifier (Amp) itself, i.e., deviation in circuit characteristics on image data, i.e., the influence of linear deviation in image density on image data must be taken into consideration.
The signal output arrangements of these CCDs will be compared. The signal outputs from the conventional 2-channel output CCD will be regarded as a sequence of pixel signals corresponding to one line of the CCD. The 2-channel output CCD outputs even and odd components arrayed in order starting from the pixel signal at the left end (appropriate array for image processing). Signal output from a CCD capable of high-speed processing, i.e., a 4-channel output CCD will be regarded as a sequence of pixel signals corresponding to one line of the CCD. The 4-channel output CCD signal outputs from the 4-channel output CCD can be considered as the sequence of pixel signals corresponding to one line of the CCD. In this case, left data of even or odd components are sequentially output starting from the pixel signal at the left end, and the pixel signal at the center is finally output from the 4-channel output CCD. Right data of even or odd components are sequentially output starting from the pixel signal at the right end, and the pixel signal at the center is finally output. Hence, the signals are not arrayed in order (inappropriate array for image processing).
These problems are not posed in the conventional 2-channel system arrangement and are unique to the 4-channel system constructed aiming at high-speed processing, and an appropriate solution means is necessary. That is, additional arrangements need be provided for the 4-channel system in consideration of these problems.
As described above, when the 4-channel output CCD is used to increase the processing speed, the influence of the difference in signal transmission path (processing path) due to the system arrangement of the preprocessing system or the internal structure of the chip of the CCD or amplifier (Amp) itself, i.e., deviation in circuit characteristics, i.e., linear deviation in image density adversely affects the image data. In addition, output signals from the 4-channel output CCD are not arrayed in order.
It is an object of the present invention to provide a photoelectric conversion apparatus, photoelectric conversion method, image information processing apparatus, image information processing method, and image forming apparatus capable of correcting deviations in image data in association with image density in use of a 4-channel output CCD and arraying image data signals.
According to the present invention, there is provided a photoelectric conversion apparatus comprising: photoelectric conversion means (D), having a plurality of elements formed in a line, for receiving light reflected by an object, photoelectrically converting the light into image signals (OS1-OS4), and outputting the image signals; first output means (101, 111, 121) for outputting the image signals received from even elements of the plurality of elements in the line in the photoelectric conversion means from a first end portion to a second end portion; second output means (102, 112, 122) for outputting the image signals received from odd elements of the plurality of elements in the line in the photoelectric conversion means from the first end portion to the second end portion; third output means (101, 113, 123) for outputting the image signals received from even elements of the plurality of elements in the line in the photoelectric conversion means from the second end portion to the first end portion; and fourth output means (102, 114, 124) for outputting the image signals received from odd elements of the plurality of elements in the line in the photoelectric conversion means from the second end portion to the first end portion.
In the present invention with this structure, instead of extracting signals from the odd- and even-numbered elements of a CCD element of one line as two channel signals, the entire screen is divided into left and right areas from the center to divide signals into four channels: signals from odd-numbered elements on the left half, signals from even-numbered elements on the left half, signals from odd-numbered elements on the right half, and signals from even-numbered elements on the right half. By processing image signals photoelectrically converted as four channel signals, high-speed image conversion processing can be realized.
In addition, according to the present invention, there is also provided a photoelectric conversion apparatus comprising: photoelectric conversion means (D), having a plurality of elements formed in a line, for receiving reflected light from an object, photo-electrically converting the light into image signals (OS1-OS4), and outputting the image signals; first output means (101, 111, 121) for outputting first image signals received from even elements from a first end portion to a central portion of the plurality of elements in the line in the photoelectric conversion means; second output means (102, 112, 122) for outputting second image signals received from odd elements from the first end portion to the central portion of the plurality of elements in the line in the photoelectric conversion means; third output means (101, 113, 123) for outputting third image signals received from even elements from a second end portion to the central portion of the plurality of elements in the line in the photoelectric conversion means; fourth output means (101, 114, 124) for outputting fourth image signals received from odd elements from the second end portion to the central portion of the plurality of elements in the line in the photoelectric conversion means; first correction means (141, 142, 160) for correcting one of the first image signal from the first output means, which is located substantially at the center of the line of the photoelectric conversion means and the second image signal from the second output means, which is located substantially at the center of the line of the photoelectric conversion means so as to make the first image signal substantially equal to the second image signal; second correction means (143, 144, 160) for correcting one of the third image signal from the third output means, which is located substantially at the center of the line of the photoelectric conversion means and the fourth image signal from the fourth output means, which is located substantially at the center of the line of the photoelectric conversion means so as to make the third image signal substantially equal to the fourth image signal; and rearrangement means (165) for rearranging, by raster processing, an order of information of the first image signal, the second image signal, the third image signal, and the fourth image signal, which are corrected by the first correction means and the second correction means.
As described above, in the present invention, correction corresponding to processing unique to four channel image signals, in which photoelectric conversion is performed while dividing the entire screen into left and right areas, is performed, and correction is performed to eliminate the difference between the left and right images. In addition, by performing raster processing for the images without any difference between the left and right images, the order of image information of four channels can be rearranged in the same order as that of image information of two channels. When raster-processed signals are used, the subsequent image processing can be realized by the conventional circuit arrangement.